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Root traits predict decomposition across a landscape-scale grazing experiment.

Smith SW, Woodin SJ, Pakeman RJ, Johnson D, van der Wal R - New Phytol. (2014)

Bottom Line: Livestock grazing increased soil temperatures, but this did not affect root decomposition.Grazing had no effect on soil moisture, but wetter soils retarded root decomposition.Our results suggest that large herbivores alter below-ground carbon and nitrogen dynamics more through their effects on plant species composition and associated root traits than through effects on the soil microclimate.

View Article: PubMed Central - PubMed

Affiliation: IBES, University of Aberdeen, St Machar Drive, Aberdeen, AB24 3UU, UK; The James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH, UK; ACES, University of Aberdeen, St Machar Drive, Aberdeen, AB24 3UU, UK.

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Loss of mass (a), carbon (b), nitrogen (c) and CO2-C efflux (d) from decomposing roots of four grass species: Agrostis capillaris, Juncus effusus, Molinia caerulea and Nardus stricta. Root decomposition for all litterbags is shown across the Glen Finglas grazing experiment (white circles) and the M. caerulea-dominated common-garden (grey circles) experiment, and species means for each experiment correspond to larger symbols (light grey circles for the main grazing experiment and dark grey circles for the common-garden experiment). The expected rates of root decomposition if soil microclimate (temperature and moisture) and/or the live species sward were the key controlling factors of root decomposition are represented by the solid grey lines, which are at the same rates of decomposition as the mean of common-garden M. caerulea roots.
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fig03: Loss of mass (a), carbon (b), nitrogen (c) and CO2-C efflux (d) from decomposing roots of four grass species: Agrostis capillaris, Juncus effusus, Molinia caerulea and Nardus stricta. Root decomposition for all litterbags is shown across the Glen Finglas grazing experiment (white circles) and the M. caerulea-dominated common-garden (grey circles) experiment, and species means for each experiment correspond to larger symbols (light grey circles for the main grazing experiment and dark grey circles for the common-garden experiment). The expected rates of root decomposition if soil microclimate (temperature and moisture) and/or the live species sward were the key controlling factors of root decomposition are represented by the solid grey lines, which are at the same rates of decomposition as the mean of common-garden M. caerulea roots.

Mentions: Despite decomposing under similar soil microclimatic conditions, mass (F3,16 = 20.52, P < 0.001), C (F3,16 = 14.75, P < 0.001) and N loss from roots (F3,16 = 38.43, P < 0.001) differed significantly among species in the common-garden experiment (Fig. 3). Species root decomposition followed a similar pattern as in the main grazing experiment. In the common-garden experiment, M. caerulea roots lost the greatest amount of mass (0.376 g g−1 ± 0.142), having lost 45, 61 and 51% more than A. capillaris, J. effusus and N. stricta, respectively, and similar differences were seen across all treatments in the grazing experiment (Fig. 3a). C loss followed a similar pattern to mass loss in the common-garden and main grazing experiments (Fig. 3b). The pattern of N loss among species did not match root mass and C loss, but followed the same species pattern in both experiments (Fig. 3c).


Root traits predict decomposition across a landscape-scale grazing experiment.

Smith SW, Woodin SJ, Pakeman RJ, Johnson D, van der Wal R - New Phytol. (2014)

Loss of mass (a), carbon (b), nitrogen (c) and CO2-C efflux (d) from decomposing roots of four grass species: Agrostis capillaris, Juncus effusus, Molinia caerulea and Nardus stricta. Root decomposition for all litterbags is shown across the Glen Finglas grazing experiment (white circles) and the M. caerulea-dominated common-garden (grey circles) experiment, and species means for each experiment correspond to larger symbols (light grey circles for the main grazing experiment and dark grey circles for the common-garden experiment). The expected rates of root decomposition if soil microclimate (temperature and moisture) and/or the live species sward were the key controlling factors of root decomposition are represented by the solid grey lines, which are at the same rates of decomposition as the mean of common-garden M. caerulea roots.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC4260134&req=5

fig03: Loss of mass (a), carbon (b), nitrogen (c) and CO2-C efflux (d) from decomposing roots of four grass species: Agrostis capillaris, Juncus effusus, Molinia caerulea and Nardus stricta. Root decomposition for all litterbags is shown across the Glen Finglas grazing experiment (white circles) and the M. caerulea-dominated common-garden (grey circles) experiment, and species means for each experiment correspond to larger symbols (light grey circles for the main grazing experiment and dark grey circles for the common-garden experiment). The expected rates of root decomposition if soil microclimate (temperature and moisture) and/or the live species sward were the key controlling factors of root decomposition are represented by the solid grey lines, which are at the same rates of decomposition as the mean of common-garden M. caerulea roots.
Mentions: Despite decomposing under similar soil microclimatic conditions, mass (F3,16 = 20.52, P < 0.001), C (F3,16 = 14.75, P < 0.001) and N loss from roots (F3,16 = 38.43, P < 0.001) differed significantly among species in the common-garden experiment (Fig. 3). Species root decomposition followed a similar pattern as in the main grazing experiment. In the common-garden experiment, M. caerulea roots lost the greatest amount of mass (0.376 g g−1 ± 0.142), having lost 45, 61 and 51% more than A. capillaris, J. effusus and N. stricta, respectively, and similar differences were seen across all treatments in the grazing experiment (Fig. 3a). C loss followed a similar pattern to mass loss in the common-garden and main grazing experiments (Fig. 3b). The pattern of N loss among species did not match root mass and C loss, but followed the same species pattern in both experiments (Fig. 3c).

Bottom Line: Livestock grazing increased soil temperatures, but this did not affect root decomposition.Grazing had no effect on soil moisture, but wetter soils retarded root decomposition.Our results suggest that large herbivores alter below-ground carbon and nitrogen dynamics more through their effects on plant species composition and associated root traits than through effects on the soil microclimate.

View Article: PubMed Central - PubMed

Affiliation: IBES, University of Aberdeen, St Machar Drive, Aberdeen, AB24 3UU, UK; The James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH, UK; ACES, University of Aberdeen, St Machar Drive, Aberdeen, AB24 3UU, UK.

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